Derechoes have been in the news in Washington as of late. No, thats not some new breed of super bureaucrat, but it is something from a supercell sized thunderstorm that crossed several states during its lifetime. You may have seen this NOAA image already on a few news websites:

Thats a time lapse radar image capture as the storm progressed from near Chicago to Chesapeake Bay.

Theyve been known over a century, and around far longer than that. Wikipedia says that Derecho comes from the Spanish word for straight.The word was first used in the American Meteorological Journal in 1888 by Gustavus Detlef Hinrichs in a paper describing the phenomenon and based on a significant derecho event that crossed Iowa on 31 July 1877.

They were further refined with the advent of weather radar. Derechos are typically bow or spearhead-shaped on weather radar, and hence they are also called a bow echo or spearhead radar echo. Heres a WSR-57 radar image from Cleveland, Ohio in 1969:

A radar in Akron, Ohio observed a bowed echo about 35 miles northwest of the radar site at 8:30 PM on the evening of July 4th (Fig. 2). This bow echo was associated with the deadly derecho winds in the Cleveland area and was one of the first radar bow echoes to be documented. Date 4 July 1969 Image: Wikipedia

They are fairly common meteorological events, occurring from May to August, peaking in frequency during the latter part of June into July. According to NOAAs Storm Prediction Center, the Washington DC area gets a derecho about once every four years:

Image from NOAA Storm Prediction Center

Heres a few of the past logged by the Storm Prediction Center.

NOTEWORTHY DERECHOS IN RECENT DECADES

Many significant derechos (i.e., those that have caused severe damage and/or casualties), have occurred over North America during the last few decades. Most of these affected the United States and Canada. Listed below is a selection of some of the more noteworthy events in recent years; the list is not all-inclusive. Information provided in the links includes a map of the area affected, and a description of the storms impact.

As the intensity of the heat wave, without reservation, was a key factor in the destructiveness of this derecho event  it raises the question about the possible role of manmade climate warming (from elevated greenhouse concentrations). Its a complicated, controversial question, but one that scientists will surely grapple with in case studies of this rare, extraordinary event.

Yet Samenow cites the same sources from the Storm Prediction Center page that I do, showing the exact same image above (after editing out the number 3). Yet somehow, he managed to conveniently ignore the historical context and the climatological frequency of derechoes on that page.

UPDATE: I made an error. I got two different posts mixed up related to the heatwave, conflating the quote discussing the heat wave by Doug Kammerer (with thunderstorm radar loop in background video by Karins on the CP post) . Ive removed the citation (and video) related to NBC Bill Karins quoted on Climate Progress. My sincere apologies for the error. My only defense is that I dont listen to audio much anymore due to my hearing issues. Thankfully, Ive got a big group of people that will let me know immediately that Ive made an error, and thus Ive heeded their advice and fixed the error within minutes of this posting. Thank you.  Anthony

I’m a good six hours south of DC and even here we had wild wind. It came on with no warning at all, no thunder or lightning, like a shockwave or something. Ten to fifteen minutes of very high wind seemingly out of nowhere, trees thrashing like a Category 1 hurricane, leaves and branches flying, numerous power outages but nothing on the scale of points north.

Thanks for posting this. Most interesting. First time I ever heard the word was last year on the Weather Channel. I don’t recall them using the term before then, but, once they did, it seemed like they had a new play toy (word) and it was repeated many times.

Likewise, TWC is doing the same with the term “haboob” which means dust storm or a big dust storm. Once again the on camera folks seemed infatuated with the word so it was used constantly. Frankly, bow echo and dust storm are much easier to understand and don’t make the meteorologist sound like arrogant twits.

I once read the diary of an Englishman during the war of 1812 who was trying to reach Detroit. He started west through North Carolina and told about the problems of trying to cross what was known then as the downed timbers.

He related in some areas it was several miles wide and hundreds of miles long where not a tree was left standing. This was result of a storm which had struck years before killing all the Indians and settlers in it’s path.

11
posted on 07/03/2012 11:06:39 PM PDT
by Sea Parrot
(Don't ever think that the reason I am peaceful is because I forgot how to be violent)

That is fascinating. And the graphic reminds me a lot of the timelapse graphics being used as examples of weather modification technology explanations made by the semifamous Dutchsinse (www.dutchsinse.com) Technology imitating nature.

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